1. Field of the Invention
This invention relates to an auto-focus apparatus.
2. Related Background Art
Various auto-focus apparatuses have heretofore been proposed and manufactured.
In an auto-focus apparatus, a light beam is received, for example, by two light-receiving portions through a photo-taking lens, and the degree of coincidence between the image patterns of the two image lights on the light-receiving portions is detected to thereby find the direction up to in-focus and the defocus amount, whereby the lens is driven by the defocus amount. In such auto-focus device, said defocus amount has been found in the stopped state of the lens to enhance the accuracy, and then the lens has been driven by the defocus amount, whereafter the defocus amount at the driven position has been again found to confirm whether the lens has been shifted to the in-focus position by the preceding lens driving, and only when the shift to the in-focus position has been confirmed as the result, the display of in-focus has been effected.
That is, in the auto-focus apparatus according to the prior art, after the defccus amount has once been detected by the focus detecting operation, the lens has been driven by the detected defocus amount and at that position, focus detection has been again effected and at this time, the judgement of in-focus has been done, whereby the indication of in-focus has been effected for the first time.
According to the above-described in-focus judging method, the indication of in-focus can be reliably effected only during the in-focus and the result of the in-focus judgement can be made high in accuracy, while after the lens driving to the in-focus position, the second focus detecting operation is necessary, and this gives rise to the problem that much time is required until the indication of in-focus.
Usually, the photographer effects the shutter releasing operation after the indication of in-focus is effected and therefore, the above-described in-focus judging and indicating system has the disadvantage of low rapidity of photographing.
To solve the above-noted problem, under a situation in which the defocus amount as a result of focus detection is below a predetermined value, that is, the lens is in the vicinity of in-focus and can be reliably shifted to the in-focus state if the lens driving based on the defocus amount is effected, it is conceivable to effect the indication of in-focus immediately after the lens driving based on the defocus amount, thereby shortening the time until the indication of in-focus. However, if the above-described system is adopted, there will arise the convenience that even if during the lens driving under said situation, the lens comes to the mechanical limit position such as the infinity position or the close distance position and any further lens driving becomes impossible, the indication of in-focus is effected immediately after the lens driving as described above.